The present invention is directed to audio systems for use in transmitting and receiving audio signals, and for the recording and playback of audio files, and more specifically, to a portable audio system that is capable of detecting a mode of use and based on that detection, automatically being configured for use in one or more of multiple modes of operation.
Embodiments of the present invention relate to portable systems that perform some combination of the functions of transmitting or receiving audio signals for a user, or recording or playing audio files for a user. Examples of such systems include mobile or cellular telephones, portable music players (such as MP3 players), and wireless and wired headsets and headphones. A user of such a system typically has a range of needs or desired performance criteria for each of the system's functions, and these may vary from device to device, and from use case to use case (i.e., the situation, environment, or circumstances in which the system is being used and the purpose for which it is being used).
For example, when listening to music while on an airplane, a user may desire high-fidelity audio playback from a device that also performs ambient noise reduction of the characteristic noise of the airplane engines. A suitable audio playback device for such situations might be a pair of high-fidelity stereo headphones with adequate passive or active noise cancellation capabilities. As another example, when driving in a car and making a telephone call via a portable telephone, a user may desire good quality noise reduction for their transmitted audio signals, while having a received audio signal that is clearly audible given the ambient noise (and which at the same time does not obscure ambient noise to a degree that causes them to be unaware of emergency vehicles, etc.). A suitable audio playback device for such a situation might be a mono Bluetooth headset with transmitted noise reduction and a suitable adaptive gain control for the received audio signal. As yet another example, when at home and on a lengthy telephone call, a user may desire a device that is very comfortable, and ambient noise reduction may be less of an issue. A suitable device for this use case might be a speakerphone with an acoustic echo cancellation function.
Audio systems are available in many forms that are intended for use in different environments and for different purposes. However, a common feature of such systems is that they are typically optimized for a limited number or types of usage scenarios, where this limited number typically does not include the full range of a user's common audio reception, transmission, recording, and playback requirements. For example, high-fidelity stereo headphones are not an optimal system for a user making a telephone call when driving a car. This is because they do not provide noise cancellation for the transmitted audio, and because they excessively block ambient noise reception to the extent that they may create a driving hazard. Similarly, a mono headset may not be optimal for a lengthy telephone call in a quiet place, because most mono headsets cannot be worn comfortably for extended periods of time.
Because existing personal audio systems that are used for a range of transmission, reception, recording, and playback operations are typically optimized for a limited range of use cases or scenarios, users typically either own and/or carry more than one device, or find that they do not have a suitable or optimal device with them when they require it. For example, it is not uncommon for users to carry both a Bluetooth headset and a pair of stereo headphones; nor is it uncommon for users to own more than one pair of stereo headphones, with each pair being optimized for a different usage situation. However, this arrangement is inconvenient and not desirable for a user; the need to own and/or carry more than one device may cost the user unnecessary money, as many of the components of one system may also be provided in another system. Alternatively, if a user does not have more than one system available, they may lose necessary or desired functionality for a given situation, such as when an owner of a pair of stereo headphones is unable to take a call while driving.
As recognized by the present inventors, there is a need for an audio system that provides some or all of the functions of reception, transmission, recording, and playback, and that provides adequate functionality when used in a wider range of usage situations than presently available systems. Such a system would have the advantage of reducing the cost to a user and improving the convenience and amount of usage a user receives from their audio system.
In this regard, it is noted that there presently exist integrated audio systems that may be used in multiple usage modes; for example, stereo headphones equipped with a microphone that may be used both for listening to music and for making a telephone call. For example, it is possible to use only one earpiece of such stereo headphones, along with the microphone, to make a call while driving. However, such presently available integrated audio systems have significant shortcomings. Typically, usage in a non-primary (i.e., alternative) mode is often uncomfortable for a user, and may not be particularly stable. This may be because the device is not designed to sit comfortably and reliably in place except in the primary position of use.
Another problem with existing integrated or multi-functional audio systems is that the audio quality, particularly with regards to ambient noise reduction on either the transmitted or received audio, is significantly worse than is desired for optimal usage. A cause of this loss of audio quality is that some audio quality features depend on the device being in a particular position; when used in a different position, the device is not in a suitable configuration for these audio quality features to operate in an optimal manner. For example, in the case where a set of stereo headphones provided with a microphone are used on a telephone call while driving with only one earpiece being used, the microphone is typically moved to a new position which is lower down on the body (it no longer being supported by both sides) or moved across to one side of the body. The new position may not be optimal for the microphone to detect the user's speech, and particularly in the case of microphones used for ambient noise reduction on the transmitted audio signal, may be less able to remove ambient noise. This is a because a common technique for removing ambient noise in transmitted audio is to use a shaped detected sound field oriented towards the user's mouth, and the movement of the microphone associated with the system being worn in a different configuration may mean the sound field is no longer optimally oriented.
Another common problem with existing integrated audio systems is that they may waste energy fulfilling incorrect or un-needed functions. For example, if a stereo headset/headphone is only being used in one ear, the energy used to drive the opposite ear's speaker is wasted, as it will not be heard. However, this speaker cannot be turned off permanently because the user might wish to put the earpiece in again at a later time. As another example, audio may be played with less gain through both ears than when played in one ear; this is both because the user is receiving two copies of the audio, and because ambient noise may be lower due to both ears being blocked by earpieces.
What is desired is a multi-modal or multi-functional audio system that enables a user to select a different configuration of the system components depending on the use case or user requirements, without suffering significant deterioration in the audio quality they require, and without loss of comfort or an inefficient use of power. Embodiments of the invention address these problems and other problems individually and collectively, and overcome the noted disadvantages of existing integrated audio systems.